1. Field of the Invention
The present invention relates to a positioning structure and a positioning method which are applied to a mobile communication terminal or the like and, more particularly, to a case and a mobile communication terminal to which the above-described positioning structure is applied.
2. Description of the Related Art
When members are incorporated in a case, it is general practice to position the members to be incorporated by the case (refer to the Japanese Patent Laid-Open No. 11-331333 and the Japanese Patent Laid-Open No. 2000-223858, for example).
However, in the Japanese Patent Laid-Open No. 11-331333 and the Japanese Patent Laid-Open No. 2000-223858, a buffering member or packing is interposed between a casing and incorporated members and, therefore, the number of parts increases, creating a possibility of a cost increase.
Therefore, there have been proposed techniques which involve positioning incorporated members by fitting a positioning convexity integrally formed on an inner surface of a case into a positioning concavity formed in a member to be incorporated (refer to the Japanese Patent Laid-Open No. 04-344112, for example). If such a positioning structure is used, incorporated members can be positioned without an increase in the number of parts.
Hereinafter, a conventional positioning structure which is applied to a cellular phone (a mobile communication terminal) will be described with reference to FIG. 7.
FIG. 7 is a partial sectional view of a cellular phone to show a positioning structure in a conventional example and, concretely, a partial sectional view of a display section in a folding cellular phone.
The appearance of the display section of a folding cellular phone shown in FIG. 7 is composed of top and bottom covers 101, 102 which constitute a case 100, a transparent panel 103 which is fitted into a display window 110a of the top cover 101, and a decorative panel 104 which covers the bottom cover 102. In the interior of the case 100, there are incorporated a display panel 105 which displays characters and the like, a lighting unit 106 which lights the display panel 105 from the back surface thereof, and a built-in frame 107 which holds these members.
The positioning of the built-in frame 107 is performed by fitting together a positioning concavity 107a formed in the built-in frame 107 and a positioning convexity 101b which is integrally formed on the inner surface of the top cover 101. And in the example shown in FIG. 7, the built-in frame 107 is fixed in a co-tightened manner by screws 108 which fix the top cover 101 and the bottom cover 102 together.
Incidentally, in the folding cellular phone shown in FIG. 7, stress is concentrated on the positioning convexity 101b if the case 100 and the built-in frame 107 are deformed by such impacts as cased by a fall. Therefore, it is preferred that strength high enough to withstand stress concentration be imparted to the positioning convexity 101b. 
However, if the size of the positioning convexity 101b is increased, a defective appearance such as shrinkage is apt to occur in the molding of the case 100 and, therefore, it is difficult to impart sufficient strength to the positioning convexity 101b, as a result of which there is a possibility that the positioning convexity 101b is broken by such impacts as caused by a fall.
Incidentally, as shown in FIG. 8, it is also conceivable to perform the positioning of the built-in frame 107 by using the periphery of a fixing boss 102a. In this case, however, it is necessary to consider the expansion of the fixing boss 102a by the tightening of the screw 108 and hence there is a limit to positioning accuracy.